The silicon carbide thin film formation process, completely performed at room temperature, was developed by argon plasma and a chemical vapor deposition using monomethylsilane gas. Time-of-flight secondary ion mass spectrometry showed that siliconcarbon bonds existed in the obtained film, the surface of which could remain specular after the exposure to hydrogen chloride gas at 800 °C. The silicon dangling bonds formed at the silicon surface by the argon plasma are considered to easily accept the monomethylsilane molecules at room temperature to produce the amorphous silicon carbide film.